La-MOF coordination polymer: An effective environmentally friendly pH-sensitive corrosion inhibitive-barrier nanofiller for the epoxy polyamide coating reinforcement

Owing to unique properties such as various structural units and crystals with specific geometric shapes, metal-organic frameworks (MOFs) are introduced as the new generation of anti-corrosion filler in recent days. In this study, for the first time, the anti-corrosion ability of the lanthanum type metal-organic framework (La-MOF) was investigated in the epoxy coating. La-MOF was synthesized via the reaction between lanthanum nitrate and terephthalic acid through a hydrothermal method. The fabricated MOF was characterized by FTIR, XRD, UV–Vis, FE-SEM, TEM, TGA, and BET tests. The corrosion inhibitive function of this nanoparticle was evaluated by the EIS test in the solution (NaCl) phase and coating (epoxy) phase. Potentiodynamic polarization (PDP) analysis has proved the oxygen (O2) reduction (cathodic) and iron dissolution (anodic) reactions control, indicating mixed inhibition impact of La-MOF on the metal corrosion. The barrier properties of the epoxy coating containing 0.5 wt% La-MOF was explored via the EIS technique. The achievements from this method showed around a 26% decline in the unfilled epoxy coating barrier performance. While the La-MOF containing epoxy coating maintained its barrier property even after 12 weeks of immersion in corrosive solutions with impedance value at the low frequency over 1010 Ω.cm2. The adhesion studies have proved that the coating adhesion was improved by 15% after the addition of the La-MOF nanoparticles.